Spiral conveyer-flight and apparatus for making same



` (No Medel.)

L e 2 sheets-sheen 1. F. C. CALDWELL. SPIRAL GONVBYER FLIGHT AND APPARATUS FOR MAKING SAME.

Ne. 601,429. Patented Mer. 29,18%.

(No Model.) 2 Sheets-Sheet 2.

. F. C. CALDWELL*l SPIRAL GONVEYER FLIGHT AND APPARATUS PoR MAKING SAME..

UNITED STATES PATENT EEICE.

FRANK C. CALDWELL, OF OAK PARK, ILLINOIS.

SPIRAL COVEYER-FLIGHT AND APPARATUS FOR MAKING SAME. l

SPECIFICATION formingpart of Letters Patent No. 601,429, dated March 29, 1898.

Application filed February 24, 1898. Serial No'. 671,521. (No model.)

To all whom it may concern.-

Be it known that I, FRANK C. CALDWELL, a citizen of the United States, residing at Oak Park, in the county of Cook, in the State of Illinois, have invented certain new and useful Improvements in Spiral Oonveyer Flights and Methods of and Apparatus for Making the Same, of which the following is a description, reference being had to the accompanying drawings, forming part of this specification.

My invention has for its obj ect the production of a continuous spiral conveyer-flight formed from a single strip of metal; and it consists in the novel means for converting a single `continuous strip of metal into such spiral convoyer-fiight and in the novel form of the conveyer-flight thus produced.

I am aware that it has heretofore been proposed in various prior patents to form a conveyerflight from a continuous strip of metal, and as a practical manufacturer of conveyerflights I am also aware that numerous attempts in this direction have been made; but to the best of my knowledge no successful method or apparatus for producing such continuous conveyer-flights has heretofore been 4 devised, and there is not now and never has been upon the market or in practical use any conveyer-flight of this description, all conveyer-flights which are now and have heretofore been in use being built up of separate sections. I have devised novel and successful means for converting a continuous strip of metal into a conveyer-flight of novel form by which the work may be easily and expeditiously accomplished with complete' success and satisfaction.

In carrying out my invention I employ a continuous strip of metal of substantially uniform thickness throughout, and I convert this strip of metal into a continuous spiral conveyer-light of Vtapering-form in cross-section by passing it between a pair of pressure-rolls of novel form and especially adapted for the purpose, as hereinafter described. Suitable guides are preferably provided to receive the spiral strip as it issues from the rolls and direct it therefrom in proper form, all as hereinafter more fully explained in connection with the accompanying drawings, in which- Figure 1 is a detail top plan View showing the two pressure-rolls, the metal strip passing between them, and the guides for receiving and directing the same; Fig. 2, a detail front elevation of the same parts; Fig. 3, an enlarged cross-section of the metal strip; Fig. 4, an enlarged detail of the rolls, showing the tapering form of the pass between them; Fig. 5, a cross-section of the strip of Fig. 3 after it has been passed between the rolls; Fig. 6, a middle longitudinal section through a piece of the completed spiral conveyer; Fig. 7, a diagram illustrating the method of determining the crosslsection of the spiral; Fig. 8, an enlarged and somewhat exaggerated view of the cross-section of a spiral as determined by the method illustrated in Fig. 7, and Fig. 9 a similar view of the two pressure-rolls.

The same letters of reference are used to represent corresponding parts in the several views. y

In the course of experiments having for their object the production of a continuousstrip spiral I have discovered that while a strip of metal of uniform thickness may be readily rolled into a disk or ring of tapering form in cross-section by passing it between a pair of truly-conical rolls having their working faces set at the proper angle to each other, it is wholly impossible to roll such strip into a helix or spiral by passing it between such rolls, no matter how proportioned and adjusted in relation to each other. In the course of repeated efforts to convert a continuous strip of metal into a spiral by means of such rolls I discovered that the difficulty and the cause of failure arose from the fact that the pass between such rolls (under any possible adjustment of them) did not conform to what would necessarily be the cross-sectionof the strip of metal when transformed into a spiral, inasmuch as the cross-section of a spiral produced from such a strip would be substantially dilferent from the cross-section of a disk or ring produced from it. Following up this discovery I ascertained, by further experiments, that if the faces of the conical rolls were so ground as to produce apass between them corresponding to what would be the exact cross-section of a strip of metal of uniform thickness when transformed into a spiral such strip could then be readily converted into spirals by passing them between IOO such rolls. As a result of these experiments I found that a spiral of any given pitch might be'formed from a continuous strip of metal of uniform thickness and of any desired width by first determining mathematically what would be the exact cross-section of such a spiral and then providing cone-like rolls so shaped and adjusted that the pass between them would correspond to such a cross-section and so proportioned that the circumference of the rolls at the one end of the pass would bear the same ratio to their circumference at the other end thereof as the length of one edge of the spiral strip to be formed bore to the length of the opposite edge thereof. Incarrying out my invention, therefore, the first step consists in determining the eX-act mathematical cross-section of the spiral to be produced and in then providing the necessary cone-like rolls having their working faces so shaped that when the rolls are properly assembled the pass between them will l .conform to the cross-section of the spiral to be produced and so proportioned that their circumference at one end of the pass-z'. e., i end of the working portion thereof-will bear the same ratio to their circumference at its opposite end as the length of one edge of the `spiral strip to be formed bears to the length; of the opposite edge thereof.

The cross-section of the spiral may be arrived at by either an arithmetical or geometrical solution of the problem. I have illustrated the latter method in Figs. 7 and 8, which may be brieiiy eX-` plained as follows: f In Fig. 7 let A C equal the circumferencel of the conveyer-flight at its outer edge, A S its l circumference at its inner edge, and A B the. pitch of the helix. vC B will then equal the length of the helix at the outer edge of the Hight and S B its length at the inner edge of the flight. Dividing the line S O (the width of the flight) into any convenient number ofl parts, A R, A Q, A P, `dre., will represent the circumference of circles concentric to A S and Within A G, and R B, Q B, P B, &c.,will represent the corresponding helices. Lines drawn from A perpendicular to the lines S B, R B,

Q B, &.c.,will intersect the latter at the points S R Q', &c. Let S B equal the thickness of@ the metal at the inner edge of the conveyerflight. Then R' B, Q B, P' B, &c., will rep-l resent the thickness of the metal at the points where the helices R B,Q B,P B, &c., are taken. Assuming now the thickness of the inner edge of the spiral which it is desired to produce to i be one-.eighth of an inch, for instance, the di mension S' B will be scaled to such thickness, l `and the dimensions R' B, Q B, &c., be then, read by the samescale. By using the thickl. nesses thus found the cross-section of the spiral may be delineated as shown4 in Fig. S and? the necessary contour of the rolls be readily determined therefrom.

In the present instance the rolls A B, Figs.. l, 2, .and 4, are formed upon the upper ends of shafts orspindles A' B', having convergent 1 axes and suitably journaled in bearings in the framework C of the machine and driven at a uniform speed by any suitable means. The circumference of the rolls at the narrower end of the working part of the tapering pass between them bears the same ratio to their circumference at the wider end thereof that the length of the outer edge of the helix to be formed bears to the length of the inner edge thereof, while at allv intermediate points the circumference of the rolls corresponds to the length of the intermediate helices of the spiral. The departure of the rolls from a truly-conical shape is not appreciable in views of the size found on Sheet l of the drawings,

but will be readily understood from Sheet 2 and the explanation heretofore given of the method of determining the shape of the rolls. When the rectangular metal strip is passed between these rolls, it is expanded from its inner toward its outer edge in exactly the proportions necessary to conform it in cross-section to the cross-section of a spiral, and the ratio of feed at all points between its opposite edges is such as to draw the strip in evenly between the rolls throughout its width 'and deliver it therefrom in the form of a spiral.

In Fig. l, E represents the metal strip, which is fed to the rolls A B through a suitable guideway F, and as it issues from the rolls it passes between two guides G G', consisting in this instance of adjustable screws mounted in supports IAI H upon the framework. against one side of the metal strip near its lower or outer edge as it issues from the rolls, while the guide G' bears against its opposite side near its upper or inner edge. These two guides are so set and adjusted as to properly direct the strip from the rolls in the spiral form shown in Figs. l and 2. The action of the rolls themselves upon the strip causes the strip to tend to issue from them in spiral form, and under some conditions and for some purposes the guides may perhaps be dispensed with; but they are advantageous and desir- ',able for insuring a uniform pitch in the spiral, even if not absolutely essential in all cases, and may be employed in the form shown or in any other suitable form for the purpose, and they may be arranged to direct the strip into a right-hand spiral or a left-handone, as

` desired.

While my invention has been designed more especially for the production of spiral conveyer-flights, and while, being a manufacturer of conveyers, that is the only use I Ahave made of it, it will be evident that it may be advantageously employed for the prof .duction of spirals for other purposes than conveyer-flights*such, for instance, as springs- ,and that spirals may be formed of strips of 'different widths and thicknesses and of varying pitch and of varying internal diameter or bore by properly arranging the size, proportions, and adjustment of the rolls.

IOO

As seen in Fig. 2, the guide G bears IIO In the practical use which I have thus far made of my invention .I have heated the metal strips before passing them through the rolls to facilitate the action of the rolls upon them; but I contemplate the employment of heavier and more powerful rolls, by which the strips may be rolled into form without heating.

Having thus fully described my invention, I claiml. As a new article of manufacture, the herein-described spiral rolled from a continuous strip of thin wrought metal of substantially uniform thickness, said spiral tapering in cross-section from its inner toward its outer edge and having its sides curved slightly inward, as set forth.

2. The herein-described apparatus for producing spirals from continuous strips of thin wrought metal, consisting of a pair of conelike pressure-rolls having convergent axes and so shaped and proportioned as to provide a tapering pass between them corresponding to a mathematical cross-section of the spiral to be produced, the circumference of said rolls at the narrower end of the pass between them bearing the same ratio to their circumference at the wider end of the pass as the length of the outer edge of the spiral to be produced bears to the inner edge thereof, and means for driving said rolls, as set forth.

3. The herein-described apparatus for producing spirals of the form specied, consisting of a pair of cone-like rolls having convergent axes and so proportioned and set relatively to each other as to provide a pass beto a mathematical cross-section of the spirall to be produced, the two guides located on opposite sides of the path of the strip as it issues from the rolls and bearing against the opposite sides of the same near its outer and in ner edges, respectively, and means for driving the rolls, as set forth.

5. The herein-described apparatus for producing spirals of the form specified, consisting of the cone-like rolls A B carried by the ends of the shafts A' B and having the taper- .ing pass between them, the guideway F for the metal strip E, located upon the entering side of the rolls, the adjustable screws G Gr located upon the opposite side of the rolls and operating as guides for the outer and inner edges of the spiral strip as it issues from the rolls, and means for driving the shafts A B',

FRANK C. CALDWELL.

-as set forth.

Witnesses EDWARD RECTOR, LEONORA WISEMAN. 

